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    <title>Document</title>
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    <!-- 编写函数norepeat(arr) 将数组的重复元素去掉，并返回新的数组

    var arr = [1, 1, 2, 3, 4, 4, 2, 1, 3, 5]
    
    function norepeat() {
      // code in here ...
    }
    
    console.log(norepeat(arr)) // [1, 2, 3, 4, 5] -->
    <script>
      var arr = [1, 1, 2, 3, 4, 4, 2, 1, 3, 5];
      var arr2 = [];
      function norepeat() {
        for (i = 1; i < arr.length; i++) {
          if (arr2.indexOf(arr[i]) == -1) {
            arr2.push(arr[i]);
          }
        }
        return arr2;
      }

      console.log(norepeat(arr2));
    </script>
    <script>
      var arr = [1, 1, 2, 3, 4, 4, 2, 1, 3, 5];
      var arr2 = [];
      for (i = 1; i < arr.length; i++) {
        if (arr2.indexOf(arr[i]) == -1) {
          arr2.push(arr[i]);
        }
      }
      console.log(arr2);
    </script>
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